I think the elves, on both sides, are probably the laziest additions of the sub races. Well, maybe not lazy, but they don't really make much sense at the moment. For the Nightborne it makes more sense for them to join the Horde, but I didn't really expect them directly after Legion, if sub races ever did appear, and Void Elves are some of the more random additions, even Pandaren made more sense, and just because one lore character is doing it suddenly there's a whole race? If they really felt like adding elves they probably should have done undead elves for the Horde and Highborne for Alliance.
I am surprised they skipped over orcs though for subraces. Having Mahgar orcs seemed the most obvious, outside of the couple versions of Tauren although they would need to update the Northrend version of Tauren to make them viable.
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Every time I see the position "Light Housekeeper" I read it as "Lighthouse Keeper". The later would be pretty cool.